Tizanidine hydrochloride is a centrally acting alpha-2 adrenergic agonist indicated for the management of spasticity. It is particularly effective in improving muscle tone and reducing the frequency and intensity of muscle spasms in conditions such as multiple sclerosis, spinal cord injury, and certain neurological disorders. This short-acting agent provides clinicians with a valuable tool for symptomatic relief, though its use requires careful consideration of its pharmacokinetic profile and potential adverse effects.

Features

• Active ingredient: Tizanidine hydrochloride
• Available in 2mg and 4mg tablet formulations
• Short half-life of approximately 2.5 hours
• Peak plasma concentration reached within 1-2 hours post-administration
• Metabolized primarily via cytochrome P450 1A2 pathway
• Excreted predominantly renal (60%) and fecal (20%)

Benefits

• Reduces painful muscle spasms and clonus
• Improves range of motion and functional capacity
• Decreases resistance to passive movement
• May enhance quality of sleep through muscle relaxation
• Allows for better performance of daily activities
• Provides flexible dosing due to short duration of action

Common use

Tizanidine is primarily prescribed for the management of spasticity resulting from multiple sclerosis, spinal cord injuries, and other neurological conditions affecting upper motor neurons. It is used both as monotherapy and as part of combination regimens with other antispasticity agents. Off-label uses include management of tension headaches, low back pain, and certain types of neuropathic pain, though evidence supporting these applications varies.

Dosage and direction

Initiate treatment with 2mg administered orally three times daily. The dose may be gradually increased in 2-4mg increments at intervals of 1-4 days based on therapeutic response and tolerability. The total daily dose should not exceed 36mg, divided into three or four administrations. Administration with food may affect absorption characteristics. For patients with renal impairment (creatinine clearance < 25 mL/min), initiate with 2mg once daily and titrate cautiously.

Precautions

Monitor liver function tests at baseline and periodically during treatment. Use with caution in elderly patients due to increased sensitivity. May cause sedation and hypotension; advise patients against operating machinery until response is known. Abrupt discontinuation may cause rebound hypertension, tachycardia, and hypertonia. Not recommended during pregnancy unless potential benefits outweigh risks. Exercise caution in patients with renal impairment.

Contraindications

Hypersensitivity to tizanidine or any component of the formulation. Concurrent use with potent CYP1A2 inhibitors such as fluvoxamine or ciprofloxacin. Severe hepatic impairment. History of orthostatic hypotension. Concomitant use with other alpha-2 adrenergic agonists.

Possible side effect

Common adverse reactions include dry mouth (49%), somnolence (48%), asthenia (41%), dizziness (16%), and hypotension (4%). Less frequently reported effects include hepatotoxicity, hallucinations, visual disturbances, and bradycardia. Most side effects are dose-dependent and may diminish with continued therapy or dose adjustment.

Drug interaction

Potent CYP1A2 inhibitors (fluvoxamine, ciprofloxacin) significantly increase tizanidine exposure. Oral contraceptives may decrease tizanidine clearance. Additive effects with other CNS depressants including alcohol, benzodiazepines, and opioids. May potentiate hypotensive effects of antihypertensive medications. Caution with concomitant use of other alpha-2 adrenergic agents.

Missed dose

If a dose is missed, administer as soon as remembered unless it is nearly time for the next scheduled dose. Do not double the dose to make up for a missed administration. Maintain regular dosing schedule to ensure consistent therapeutic effect.

Overdose

Symptoms may include profound sedation, respiratory depression, hypotension, bradycardia, and coma. Management involves supportive care including airway protection, cardiovascular monitoring, and symptomatic treatment. Activated charcoal may be beneficial if administered promptly. There is no specific antidote; hemodialysis is not effective due to high protein binding.

Storage

Store at controlled room temperature (20-25°C or 68-77°F). Protect from light and moisture. Keep in original container with tight closure. Keep out of reach of children and pets. Do not use beyond the expiration date printed on packaging.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before starting or changing any medication regimen. Individual response to medication may vary. Proper diagnosis and monitoring are essential for safe and effective treatment.

Reviews

Clinical studies demonstrate tizanidine’s efficacy in reducing muscle tone and spasm frequency. In randomized controlled trials, 60-70% of patients experienced significant improvement in spasticity scores compared to placebo. Patient reports frequently note improved mobility and reduced pain, though sedation remains a common concern. Long-term studies suggest maintained efficacy with appropriate dose titration and monitoring.